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Biomedical subjects

A Beaumont

Publications and source records attributed to A Beaumont.

At least 73 records · Page 4Linked to original sources
PubMed1985

Arterial oxygen desaturation during treadmill and bicycle exercise in patients with chronic obstructive airways disease.

Nine men with severe chronic obstructive airways disease (COAD), known to desaturate on exercise, performed a 6 min self-paced walk on a treadmill, followed by a bicycle exercise with workloads adjusted to mimic the oxygen consumption achieved on the treadmill. During both exercises, ventilation, oxygen consumption, carbon dioxide production, PaO2, PaCO2, pH and arterial lactate were measured and subjective breathlessness recorded. A reasonable match of oxygen consumption between the two exercises was achieved. In all subjects PaO2 fell to a lower level during treadmill compared with bicycle exercise. Ventilation, carbon dioxide production and arterial lactate were higher during bicycle exercise. Subjective breathlessness was greater during bicycle exercise, in proportion to the higher ventilation on the bicycle. The greater anaerobiosis occurring on the bicycle led to acidosis and an increased ventilation, minimizing the exercise fall in PaO2. Bicycle testing may seriously underestimate exercise desaturation occurring during level walking in patients with severe COAD.

Aged↗
PubMed1985

Identification of a proenkephalin precursor in striatal tissue.

Recent studies have supported the suggestion that proenkephalin is the same in both adrenal medulla and brain. However, although previous investigations have characterized enkephalin-containing adrenal intermediates derived from proenkephalin, as yet no such intermediates have been isolated from the brain. This has led to the belief that the processing of proenkephalin in the brain is extremely rapid and enkephalin-containing intermediates do not accumulate. In this investigation Sephacryl-300 gel filtration chromatography of guinea pig striata, extracted in 8 M urea, demonstrated several peaks of both bioactive and immunoreactive enkephalin-like peptides after enzymatic digest (trypsin followed by carboxypeptidase B). Comparable profiles were obtained using rat and bovine striatal tissue. In guinea pig the major species emerging from gel filtration, eluting with an apparent molecular weight of 29,000, represented approximately 9% of the total (methionine) enkephalin immunoreactivity. It had an apparent pI of 5.0 when subjected to chromatofocusing. This species was further characterized using sodium dodecyl sulphate-polyacrylamide gel electrophoresis and nitrocellulose blotting techniques as well as highly specific radioimmunoassays to (Met5)-enkephalin, (Leu5)-enkephalin, and (Met5)-enkephalin-Arg6-Phe7. This species was found to contain these opioid peptides in an approximately 6:1:1 ratio, respectively, and to have an apparent molecular weight of 31,000. It was also indicated that (Met5)-enkephalin-Arg6-Phe7 constituted the C-terminal seven residues of this molecule.

Animals↗
PubMed1985

Ultrastructural changes in the rat thyroid gland during iodine deficiency.

Thyroid ultrastructure changes were studied during the course of a low iodine diet in rats. At day 20, follicles were normal, but a number of them contained cells of higher density and with greatly elongated microvilli. Endoplasmic reticulum cisternae were frequently dilated. From day 20 until day 80, the most characteristic changes in the thyroid cells were the progressive accumulation of subapical peroxidase-positive exocytotic vesicles. After 80 days of the low iodine treatment, Golgi apparatuses were very active. Cell division could be observed. At this stage, exocytotic vesicles were generally very abundant. These data suggest that the remarkable accumulation of subapical exocytotic vesicles between day 20 and day 120 might represent an adaptation to the moderate and gradual increase in TSH stimulation that occurs in the conditions of low iodine diet.

Animals↗
PubMed1985

A self paced treadmill walking test for breathless patients.

A treadmill exercise test is described that retains the advantages of self paced walking but allows the measurement of cardiorespiratory variables. A horizontal treadmill was modified to allow patients to control their own speed. During exercise continuous measurements of speed, distance, heart rate, arterial oxygen saturation, and stride length were made and subjective assessments of breathlessness were recorded on a visual analogue scale. Ten men with severe chronic obstructive lung disease performed a 12 minute corridor walk and a self paced 12 minute treadmill walk on the same day and repeat treadmill walks on different days. Six of them performed three walks or more. Six patients had ventilatory measurements during treadmill exercise. There was no significant difference (p greater than 0.1) in the distance covered during corridor and treadmill walks, and distances on the treadmill were repeatable after the first walk. Use of a mouthpiece significantly reduced the distance covered on the treadmill. The self paced treadmill walk is a simple repeatable test and has advantages over both a corridor walking test and standard progressive tests for assessment of breathless patients.

Aged↗
PubMed1984

Ultrastructural localization of immunoreactive calcitonin in the two cell types of the ultimobranchial gland of the common toad (Bufo bufo L.).

The ultimobranchial (UB) glands of the common toad Bufo bufo consist of several cellular masses containing two quite different cell types which line a central lumen filled with amorphous material. The morphologically defined Type I cell is akin to a typical calcitonin secretory cell as observed for all vertebrates, with small dense-core secretory granules. On the contrary the Type II cell displays large apical dense bodies which may be related to the secretion and/or absorption of the amorphous material. Cells morphologically related to Type II cells have been described in the UB glands of Sauropsidea and in the UB follicles of mammalian thyroid gland. An immunocytochemical stain using an antiserum raised against synthetic salmon calcitonin demonstrated the specific localization of an immunoreactive product in both Type I and Type II cell granules, suggesting that both cell types could be involved in calcitonin metabolism. Moreover, the presence of immunoreactive calcitonin in the Type II cells of the Bufo UB gland raises the question of the function of the morphologically equivalent cells of other species.

Animals↗
PubMed1983

[Epithelioma of the lacrimal sac. Review of the literature and analysis of 8 cases].

Eight patients with lacrimal sac epitheliomas are reported and the published literature reviewed. Clinical signs of these very particular type of tumor are described, as well as their method of extension to the upper facial region which has now been perfectly documented by computed tomography images. Papillomatous forms are relatively frequent, progression of the tumors is slow, and the prognosis for recurrences is fairly good if extensive surgery has been applied.

Adult↗
PubMed1981

The fine structure of papillary carcinoma of the thyroid.

Eight human thyroid cancers (four papillary, and four lymph node metastases of papillary cancers) were studied at the ultrastructural level. The most characteristic anomalies affect the nucleus: "ground glass nuclei", highly indented nuclear membrane with formation of nuclear pseudoinclusions, nuclear bodies probably of nucleolar origin, fractionation of the periphery of the nucleus into multiple lobes joined by thin bridges of nuclear substance. Other abnormalities related to the mitochondria with decrease of size and number of cristae, the rough endoplasmic reticulum which was segregated in parallel saccules and the basal lamina was often reduplicated. The significance of these anomalies is discussed.

Carcinoma, Papillary↗
PubMed1980

Opioid peptides: aspects of their origin, release and metabolism.

At the present time there is evidence for two families of related peptides which act as ligands for opiate receptor sites. The endorphin group of peptides are derived from the ACTH/LPH precursor pro-opiocortin. The enkephalins appear to be formed from a separate precursor or precursors that have yet to be fully characterized. There appear to be a number of different types of opiate receptors and this may be related to the multiplicity of peptide ligands that have so far been identified. The enkephalins and related peptides appear to have a much wider distribution than the endorphins but the latter may act as circulating hormones unlike the enkephalins. It is likely that both endorphins and enkephalins are involved in sensory modulation processes and release of these peptides has been demonstrated during brain stimulation for pain relief. The enkephalins are very rapidly inactivated by tissue proteases, the aminopeptidases appear largely responsible for the inactivation of exogenously administered enkephalins but the dipeptidyl carboxypeptidase, termed enkephalinase, may have a special inactivating function at enkephalinergic synapses. Evidence will be presented for the biosynthesis, the release and inactivation of the enkephalins relating to the above points.

Amino Acid Sequence↗
PubMed1979

Studies on the neurochemical properties of cystathionine.

Following the intracerebral administration of [35S]cystathionine, the synaptosome fraction of rat brain was labelled, the greatest uptake of amino acid being associated with hypothalamus. The uptake of [35S]cystathionine by synaptosome preparations isolated from different regions of brain, was typical of that exhibited by amino acids which are not neurotransmitters. Depolarization of the synaptic membrane had no effect on the efflux of [35S]cystathionine from preloaded synaptosomes. The intracerebral administration of cystathionine resulted in an elevation of the levels of brain cyclic AMP, the effect being particularly evident in the cerebellum. Attempts to reproduce this effect in vitro were unsuccessful.

Adenylyl Cyclases↗
PubMed1976

[ Perfecting a simple method of organotypic thyroid gland culture in Xenopus laevis (Amphibia, Anoura)].

The larval thyroid of Xenopus cultured in an adequate medium, keeps its morphological differentiations at an ultrastructural scale and reacts against TSH added to the culture medium, through the development of apical microvilli, which is a sign of an active pinocytosis of the colloid, and also of ergastoplasmic lamellar and vesicular structures suggesting an active protein synthesis.

Animals↗
PubMed1975

[Ultrastructure of the larval pancreas of an anuran amphibian, Alytes obstetricans L, in organ culture].

Different techniques have been used to realise organ culture of larval pancreas of Alytes obstetricans Laur. Some methods allow to get satisfaction results. The general aspect of the explant is described, as also the ultrastructure of the different parts of the pancreas. The results allow to consider the experimental study of the in vitro metamorphosis under the influence of thyroxine.

Animals↗